Company says "sour water" release contained the chemical mercaptan

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Shell officials have vowed to continue investigating Friday’s leak at its Corunna refinery, which caused several roads to be shut down and school buses to be held after a shelter in place was issued.

Officials from St. Clair Township, the City of Sarnia and Aamjiwnaang’s environmental committee met with company officials Monday.

Shell plant manager Michele Harradence said some concern has been raised over the communication of the shelter in place.

“There was some confusion,” Harradence said after Monday’s meeting. “At one point, minutes before we were going to lift the shelter in place, there was some confusion around extending it north. That was out of the hands of Shell at that point.”

Shell called for a shelter in place just before 2 p.m. Friday after a strong smell was eminating from the refinery. A CVECO Code 6 was also issued, resulting in police blocking all southbound traffic at River Road, Tashmoo Avenue and Highway 40.

Shell issued the all-clear around 3:30 p.m.

Harradence said the shelter in place was issued as a precaution until officials could determine the source of the smell.

Officials traced the smell back to the flare collection system, which holds sour water.

This liquid contains light crude oil components, which can include hydrogen sulfide and mercaptan.

“Mercaptan and H2S (hydrogen sulfide) smell a lot alike,” Harradence said. “Some will say mercaptan smells like rotten cabbages versus H2S smells like rotten eggs. We feel they’re very difficult to distinguish between the two, so as a result, when we saw the leak that we had and given the odour, we chose to err on the side that it was H2S because we knew there was the potential for H2S in the line.”

Even low concentrations of hydrogen sulfide can be extremely toxic, according to a report prepared by the Canadian Association of Petroleum Producers. Health effects can include headaches, drowsiness, and irritation of the eyes, nose and throat.

Company officials were able to later confirm it was a mercaptan leak.

When asked if there are any health effects from exposure to mercaptan, Harradence said the company isn’t aware of any.

“The smell of it is an unpleasant smell for sure, but in terms of either short-term or long-term health effects, we’ve advised that no there aren’t,” she said.

However, Aamjiwnaang resident Ada Lockridge said she heard from some residents who complained of red and swollen eyes, as well as headaches.

“I don’t know what levels we were exposed to and what it can do to us,” she said.

Kim Henry, a supervisor at the day care, said its children, staff and some parents will hold an Idle No More demonstration Wednesday that is also in reaction to Friday’s incident.

Henry said staff at the centre began noticing an odour before noon Friday.

“They could smell that rotten egg smell,” Henry said.

“They had to shut the heat system right off and close everything up.”

Henry said the staff, children and parents are planning to leave the centre at 10 a.m. Wednesday and walk to the St. Clair Parkway. They will rally there, alongside the River Road, for about one hour.

“What we’re trying to say is that we’ve had enough of the pollution,” Henry said.

Kate Jordan, spokesperson for Ontario’s Environment Ministry, said the spill was contained on Shell’s property and the equipment involved repaired over the weekend.

Ministry officials inspected the site Friday and instructed Shell to undertake air monitoring around the facility, Jordan said.

“The air monitoring did not show any levels of concern and the results were shared with the local health unit and the nearby First Nations community,” she said.